The present invention relates to electric traction motor vehicles having a traction motor in each of the driving wheel. It can be used both on purely electric vehicles and on vehicles of the series hybrid type.
In some of the cases mentioned above, it is considered desirable to have a choice of reduction gears between the electric motor and the wheel. The traction chain therefore comprises a gear change mechanism which makes it possible either to obtain a high torque on the wheel or to reach the maximum speed of the vehicle. The problem then arises of how to carry out the gear change in a manner that is as gentle and imperceptible as possible. In this respect, reference can be made to the following publications: U.S. Pat. Nos. 5,879,265, 5,498,216, 4,593,580, 5,688,205, 5,741,202, 4,505,368 et U.S. 2002/0023791.
However, all these devices need complex or costly means to ensure a ratio change as gently as possible.
The aim of the invention is to control the gear change on the driving wheels by using as far as possible means that are integrated with other functions so as to avoid any pointless complexity and source of failure.